1. Field of the Invention
The present invention relates to a blasting device, in particular for cleaning the surfaces of hollow areas or cavities by means of a jet stream including a conveying or carrier medium, preferably air, and a solid blasting material added to the jet stream.
2. The Prior Art
The cleaning of surfaces by a jet of solid particles that are accelerated by means of a conveying medium, for example a carrier air stream, is a commonly-employed surface cleaning method. In the metal-processing industry, corroding unfinished parts are first cleaned by sandblasting, as a rule, before such parts are processed further. The cleaning of curved surfaces and in particular of surfaces of cavities has been found to require much expenditure. The only opening leading to the cavity is frequently small, so that blasting devices are needed that are specially adapted to the particular cavity.
A special field of application exists in the area of the cleaning of the inner surfaces of pipes especially in connection with large condensers. Particularly in the field of energy generation, the pipeline system of a condenser often has lost the desired heat transfer and the corresponding density (or concentration) due to corrosion or accumulation of dirt. Such soiling is reflected by serious losses in the degree of efficiency. The occurring loss of capacity requires a new pipeline system for the condenser in most cases, or the existing, old pipeline system has to be restored. To restore the pipeline system of a heat exchanger, it is necessary in any event to clean the inside surfaces of the pipes.
For this purpose, it is already known to clean the individual pipes from the inside by blasting with the use of a special blasting device that is axially displaced in the individual pipes. Different types of blasting agent are employed in this cleaning process. However, the blasting operation requires much time because the rate at which the blasting nozzle is employed with the axial method has to be selected sufficiently low for each individual pipe, in order to obtain the desired cleaning effect. This time-consuming cleaning operation is frequently the primary factor that determinates the time schedule within the framework of a power plant revision. The duration of the blasting operation of the individual pipes consequently has a direct effect on the availability of the power plant, and any change is connected with economic losses. Moreover, a large quantity of blasting agent is required in most cases.
For cleaning the inside surfaces of pipes in particular during a restoration of the existing pipeline system of heat exchangers, a blasting device would be desirable that can be mounted on the ends of the pipes and that dispenses the blasting agent into the pipe to be cleaned with a high spin (or twist) and at a high blasting rate. In this way, the blasting agent will clean the pipe abrasively by means of the impressed spin, and will pass in a cleaning manner over the entire length of the pipe under the pressure of the conveying medium. In a case in which different pipe widths have to be cleaned, quick adaptability of the nozzle component of a blasting device would be desirable, as it would be desirable to have the possibility for mounting the blasting device on the pipe attachment so that it projects into the starting area of the pipe to be cleaned.
Furthermore, easy exchangeability of the components of the blasting device that are stressed most would be desirable because of the strong abrasive effect exerted by the blasting agent.